Torque measurement device and program

ABSTRACT

To provide a torque measurement device capable of more accurately specifying positions of reflectors which are attached to a rotating body, and more accurately obtaining a torque of the rotating body. 
     A pair of reflectors ( 14   a,    14   b ) is provided on the surface of the rotating body ( 13 ) and has a spacing in the axial direction, reflected light data obtained by reflection of reflection patterns in the pair of reflectors ( 14   a,    14   b ) is input and stored, a point of minimizing AIC is determined for a model of the reflected light data from the rotating body ( 13 ), and existence regions of the pair of reflectors ( 14   a,    14   b ) are detected. Then, a twist amount of the rotating body ( 13 ) is calculated from the reflector positions specified by the detected existence regions of the pair of reflectors ( 14   a,    14   b ), and the torque is calculated from the calculated twist amount of the rotating body.

TECHNICAL FIELD

The present invention relates to a torque measurement device and atorque measurement program, which measure a rotating speed and an axialtorque of a rotating body optically in a non-contact mode.

BACKGROUND ART

There has been developed an optical torque measurement device fordetecting a torque of a drive axis (rotating body) in rotating equipmentsuch as a gas turbine and a steam turbine, for the purpose ofidentifying a cause of change in a thermal efficiency of acombined-cycle generating plant or a steam turbine plant, for example.This torque measurement device provides a pair of reflectors atdifferent positions on the rotating body in the axial direction thereof,irradiates both of the reflectors with laser light and detects reflectedlight thereof from both of the reflectors, obtains a rotation period ofthe rotating body from periodical strong and weak intensities of thereflected light, and detects a torque of the rotating body from a delaytime of the reflected light between the reflectors (refer to Patentdocument 1, for example).

In such a torque measurement device, extraction of the reflected lightdata necessary for signal processing, yes-no judgment of a processedresult in the signal processing, or the like, is operated manually by ananalyzer and takes a long time for the analysis job thereof.Accordingly, there is a technique that specifies a reflection patternposition of the reflected light reflected by the reflector, which isprovided to the rotating body, automatically using a signal processingdevice, calculates the rotation period or a twist amount of the rotatingbody from data within a reflection pattern range determined by thespecified reflection pattern position, automatically using the signalprocessing device, and calculates the torque from the calculated twistamount of the rotating body (refer to Patent document 2, for example).

Patent document 1: Japanese Unexamined Patent Application PublicationNo. 2002-22564

Patent document 2: Japanese Unexamined Patent Application PublicationNo. 2005-16950

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, when the analyzer manually extracts the reflected light data ofthe reflectors, which is necessary for the signal processing, theanalysis job takes a long time and also the extraction of the reflectedlight becomes inaccurate, if the reflected light data contains noise.

Further, the technique of Patent document 2 reads the reflected lightdata of the reflectors on the rotating body, generates a trigger valuebased on the maximum and minimum values of the read reflected lightdata, and determines a region having a value exceeding the trigger valueto be a reflection pattern region of the reflector. Although thetechnique can specify the position of the reflector automatically, sincecalculating the trigger value by multiplying a difference between themaximum and minimum values by a certain ratio, the technique sometimescannot accurately specify the position of the reflector depending on howto determine the ratio. If the position of the reflector is notaccurate, the torque calculated therefrom also has an error.

An object of the present invention is to provide a torque measurementdevice and a torque measurement program which can more accuratelyspecify the positions of the reflectors attached to the rotating bodyand can more accurately obtain the torque of the rotating body.

Means for Solving the Problems

The torque measurement device according to a first aspect of theinvention is provided with: a laser light output device outputting laserlight; a light transmitting/receiving device irradiating a surface of arotating body with the laser light from the laser light output deviceand also receiving reflected light thereof; a pair of reflectors whichis provided on the surface of the rotating body, having a spacing in anaxial direction thereof, and reflects the irradiating laser light fromthe light transmitting/receiving device in a predetermined reflectionpattern; and a signal processing device obtaining a torque of therotating body from the reflected light received by the lighttransmitting/receiving device, wherein the signal processing deviceincludes: an input data storage section storing reflected light data ofthe laser light irradiating the surface of the rotating body, thereflected light data being input according to rotation of the rotatingbody; a reflector existence-region detection unit detecting existenceregions of the pair of reflectors by determining a point which minimizesAIC of a model for the reflected light data of the rotating body, thereflected light data being stored in the input data storage section; atwist amount calculation unit calculating a twist amount of the rotatingbody from reflector positions which are specified by the existenceregions of the pair of reflectors, the existence region being detectedby the reflector existence-region detection unit; and a torquecalculation unit calculating a torque from a twist amount of therotating body, the twist amount being calculated by the twist amountcalculation unit.

The torque measurement device according to a second aspect of theinvention is provided with: a laser light output device outputting laserlight; a light transmitting/receiving device irradiating a surface of arotating body with the laser light from the laser light output deviceand also receiving reflected light thereof; a pair of reflectors whichis provided on the surface of the rotating body, having a spacing in anaxial direction thereof, and reflects the irradiating laser light fromthe light transmitting/receiving device in a predetermined reflectionpattern; and a signal processing device obtaining a torque of therotating body from the reflected light received by the lighttransmitting/receiving device, wherein the signal processing deviceincludes: an input data storage section storing reflected light data ofthe laser light irradiating the surface of the rotating body, thereflected light data being input according to rotation of the rotatingbody; an approximate reflector-position detection unit detectingapproximate positions of the pair of reflectors from the reflected lightdata of the rotating body, the reflected light data being stored in theinput data storage section; a reflector existence-region detection unitdetecting existence regions of the pair of reflectors by determining apoint which minimizes AIC of a model for a pair of the reflected lightdata in neighborhoods of the approximate reflector positions which aredetected by the approximate reflector-position detection unit; a twistamount calculation unit calculating a twist amount of the rotating bodyfrom reflector positions which are specified by the existence regions ofthe pair of reflectors, the existence region being detected by thereflector existence-region detection unit; and a torque calculation unitcalculating a torque from a twist amount of the rotating body, the twistamount being calculated by the twist amount calculation unit.

The program according to a third aspect of the invention enables acomputer to carry out a method including the steps of: inputting andstoring reflected light data obtained by reflection of reflectionpatterns in a pair of reflectors which is provided on a surface of arotating body and has a spacing in an axial direction thereof; detectingexistence regions of the pair of reflectors by determining a point whichminimizes AIC of a model for the reflected light data of the rotatingbody; calculating a twist amount of the rotating body from reflectorpositions specified by the detected existence regions of the pair ofreflectors; and calculating a torque from the calculated twist amount ofthe rotating body.

The program according to a fourth aspect of the invention enables acomputer to carry out a method including the steps of: inputting andstoring reflected light data obtained by reflection of reflectionpatterns in a pair of reflectors which is provided on a surface of arotating body and has a spacing in an axial direction thereof; detectingapproximate positions of the pair of reflectors from the reflected lightdata of the rotating body; detecting existence regions of the pair ofreflectors by determining a point which minimizing AIC of a model forthe reflected light data in neighborhoods of the detected approximatepositions of the pair of reflectors; calculating a twist amount of therotating body from reflector positions specified by the detectedexistence regions of the pair of reflectors and calculating a torquefrom the calculated twist amount of the rotating body.

Advantages of the Invention

The present invention detects the existence region of the pair ofreflectors by determining the point which minimizes AIC of the model forthe reflected light data of the rotating body, which is obtained by thereflection of the pair of reflectors provided on the surface of therotating body having the spacing in the axial direction, and thereby adetection accuracy of the reflector positions is improved. Therefore, anaccuracy of the torque calculated from the reflector positions isimproved.

Further, the present invention detects the approximate positions of thepair of reflectors by the reflected light data of the rotating body anddetects the existence region of the pair of reflectors by determiningthe point which minimizes AIC of the model for the reflected light datain the neighborhoods of the approximate positions of the pair ofreflectors, and thereby it is possible to detect the reflector positionsquickly and also accurately.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block configuration diagram of a torque measurement deviceaccording to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of an AICp calculation range of a modelfor reflected light data in the first embodiment of the presentinvention.

FIG. 3 is an explanatory diagram of an AICp calculation result of themodel for the reflected light data in the first embodiment of thepresent invention.

FIG. 4 is an explanatory diagram of the reflected light data obtainedfrom a pair of reflectors in the first embodiment of the presentinvention.

FIG. 5 is a flowchart showing a torque measurement method measuring atorque using the torque measurement device according to the firstembodiment of the present invention.

FIG. 6 is a block configuration diagram of a torque measurement deviceaccording to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of range average processing in anapproximate reflector-position detection unit in the second embodimentof the present invention.

FIG. 8 is an explanatory diagram of approximate reflector-positiondetection processing in the approximate reflector-position detectionunit of the second embodiment of the present invention.

FIG. 9 is a flowchart showing a torque measurement method measuring atorque using the torque measurement device according to the secondembodiment of the present invention.

DESCRIPTION OF THE SYMBOLS

11: Laser light output device, 12: Light transmitting/receiving device,13: Rotating body, 15: Light detection device, 16: Signal processingdevice, 17: Signal input processing unit, 18: Input data storagesection, 19: Reflector existence-region detection unit, 20: Twist amountcalculation unit, 21: Torque calculation unit, 22: Output processingunit, 23: Output device, 24: Approximate reflector-position detectionunit

BEST MODES FOR CARRYING OUT THE INVENTION First Embodiment

FIG. 1 is a block configuration diagram of a torque measurement deviceaccording to a first embodiment of the present invention. Laser lightoutput from a laser light output device 11 irradiates the surface of arotating body 13 via a light transmitting/receiving device 12. A pair ofreflectors 14 a and 14 b is provided on the surface of the rotating body13, having a spacing in the axial direction, and reflects theirradiating laser light from the light transmitting/receiving device 12in a predetermined reflection pattern. Each of the reflectors 14 a and14 b has a reflection pattern which is formed in a bar-code patternhaving a portion reflecting the laser light and a portion absorbing thelaser light, for example, and generates reflected light according to thereflection pattern when irradiated by the laser light. The reflectedlight reflected on the surface of the rotating body 13 including thereflectors 14 a and 14 b is received by the light transmitting/receivingdevice 12, and reflection intensity thereof is detected by lightdetection devices 15 a and 15 b and input into a signal input processingunit 17 of a signal processing device 16. In the following description,there will be described a case in which one set of the pair ofreflectors 14 a and 14 b is provided around the rotating body 13.

The signal processing device 16 obtains a rotation period and a twistamount of the rotating body 13 using the reflected light reflected bythe pair of reflectors 14 a and 14 b within the reflected lightreflected by the surface of the rotating body 13, and further obtains atorque. The signal input processing unit 17 of the signal processingdevice 16 carries out filtering processing, for example, of the inputreflected light data of the rotating body 13 and stores the reflectedlight data in each rotation of the rotating body 13 into an input datastorage section 18 for a predetermined number of rotations.

A reflector existence-region detection unit 19 detects existence regionsof the pair of reflectors 14 a and 14 b from the reflected light data ofthe rotating body stored in an input data storage section 18; inputs thereflected light data of the rotating body 13 stored in the input datastorage section 18 sequentially in a time series and specifies positionsof the reflectors 14 a and 14 b in real time using an arithmetic methodto be described hereinafter.

The reflector positions specified by the reflector existence-regiondetection unit 19 are input into a twist amount calculation unit 20. Thetwist amount calculation unit 20 calculates a twist amount of therotating body 13 in real time from the specified reflector positions.The twist amount of the rotating body 13 calculated by the twist amountcalculation unit 20 is input into a torque calculation unit 21, and thetorque calculation unit 21 calculates a torque of the rotating body 13in real time from the twist amount of the rotating body calculated bythe twist amount calculation unit 20. The torque of the rotating body 13calculated by the torque calculation unit 21 is provided with outputprocessing in an output processing unit 22 and output to outside fromthe signal processing device 16. FIG. 1 shows a case of outputting to anoutput device 23.

Next, the arithmetic method, which calculates the existence region ofthe reflector in the reflector existence-region detection unit 19, willbe described. Waveform data stored in the input data storage section 18for the reflected light data of the rotating body is composed ofwaveform data in a region where the reflection pattern of the reflector14 a or 14 b exists and waveform data in a region where the reflectionpattern does not exists, which regions have different characteristics.

Accordingly, there are assumed two waveform data models for thereflected light data stored in the input data storage section 18; awaveform data model M1 which does not have the reflected light patternof the reflector 14 a or 14 b and a waveform data model M2 in the regionwhere the reflection pattern exists. Then, AIC (Akaike's InformationCriterion) is obtained for a reflected light data model M including themodel M1 and the model M2, and a point which minimizes AIC of thereflected light data model M is determined for detecting the existenceregions of the pair of reflectors 14 a and 14 b. That is, a startingposition and an ending position for each of the reflectors 14 a and 14 bare detected, and the existence regions of the pair of reflectors 14 aand 14 b are detected.

Here, AIC is expressed by the following formula (1). L is a maximumlikelihood and log(L) is a maximum logarithm likelihood.[Formula 1]AIC=−2×log(L)+2×(Number of parameters)  (1)Now, both of the waveform data model M1 for the region without thereflector pattern and the waveform data model M2 for the region with thereflector pattern utilize the range average values for the models. Then,the range average value of the model M1 is nearly zero, and the rangeaverage value of the model M1 is a value corresponding to a reflectedlight level of the reflection pattern. Therefore, focusing on thereflected light data model M including the model M1 and the model M2, apoint for the best fitting of the reflected light data model M is aboundary point between the model M1 and the model M2. That is, the pointof minimizing AIC is determined for the reflected light data model M andthe starting point and the ending point for each of the pair ofreflectors 14 a and 14 b are detected, and then the existence regions ofthe pair of reflectors 14 a and 14 b are detected.

From the above, the reflected light data model M is divided into twomodels Ma and Mb hypothetically, and the maximum likelihood La of themodel Ma is assumed to be expressed by Formula (2-1) and the maximumlikelihood Lb of the model Mb is assumed to be expressed by Formula(2-2).

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 2} \right\rbrack & \; \\{L_{a} = {\left( \frac{1}{\sqrt{2\pi}} \right)^{N}\left( \sigma_{a}^{2} \right)^{- \frac{N}{2}}{\mathbb{e}}^{- \frac{N}{2}}}} & \left( {2\text{-}1} \right) \\{L_{b} = {\left( \frac{1}{\sqrt{2\pi}} \right)^{N}\left( \sigma_{b}^{2} \right)^{- \frac{N}{2}}{\mathbb{e}}^{- \frac{N}{2}}}} & \left( {2\text{-}2} \right)\end{matrix}$

N is the number of object ranges, e is a base of a logarithm, d_(a) ² isa dispersion of the waveform data in the region without the reflectionpattern, d_(b) ² is a dispersion of the waveform data in the region withthe reflection pattern, and the dispersion d_(a) ² is expressed byFormula (3-1) and the dispersion d_(b) ² is expressed by Formula (3-2).

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 3} \right\rbrack & \; \\{{\sigma_{a}^{2}(p)} = {\frac{1}{p}{\sum\limits_{j = 0}^{p}\left( {x_{j} - {\overset{\_}{x}}_{a}} \right)^{2}}}} & \left( {3\text{-}1} \right)\end{matrix}$

p is a parameter, and x _(a) is a range average value.

$\begin{matrix}{{\sigma_{b}^{2}(p)} = {\frac{1}{N - p - 1}{\sum\limits_{j = {p + 1}}^{N}\left( {x_{j} - {\overset{\_}{x}}_{b}} \right)^{2}}}} & \left( {3\text{-}2} \right)\end{matrix}$

p is a parameter, x _(b) is a range average value, and N is the numberof data sets.

Next, Formula (2-1) is substituted into Formula (1), and Formula (4-1)is obtained for calculating AICa of the model Ma. In this case, theparameter is only p and the number of parameters becomes 1. Similarly,Formula (2-2) is substituted into Formula (1) and 1 is substituted forthe number of parameters, and then Formula (4-2) is obtained forcalculating AICb of the model Mb.[Formula 4]AIC_(a)={(p+1)(log(2πσ_(a) ²)+1)+2}  (4-1)AIC_(b)={(N−p)(log(2πσ_(b) ²)+1)+2}  (4-2)

Then, AICp for the reflected light data model M is obtained as a sum ofAICa and AICb as shown in Formula (5).

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 5} \right\rbrack & \; \\\begin{matrix}{{AIC}_{p} = {{AIC}_{a} + {AIC}_{b}}} \\{= {\begin{Bmatrix}\left( {p + 1} \right) \\{\left( {{\log\left( {2{\pi\sigma}_{a}^{2}} \right)} + 1} \right) + 2}\end{Bmatrix} + \begin{Bmatrix}\left( {N - p} \right) \\{\left( {{\log\left( {2{\pi\sigma}_{b}^{2}} \right)} + 1} \right) + 2}\end{Bmatrix}}}\end{matrix} & (5)\end{matrix}$

FIG. 2 is an explanatory diagram of a calculation range of AICp. Forexample, an AICp value expressed by Formula (5) is obtained by changingthe parameter p for the number of data sets N in the object range H1 ofthe reflected light data. When the object range H1 includes the startingposition (p=p₀) of the reflection pattern of the reflector, the AICpvalue becomes smaller gradually and increases abruptly from a minimumvalue, as the parameter p increases, as shown in FIG. 3. The position ofthis minimum value (p=p₀) is the starting position of the reflector.

On the other hand, when the object range H2 includes the ending position(p=p₀₁) of the reflection pattern of the reflector as shown in FIG. 2,the AICp value becomes smaller gradually and reduces abruptly to be aminimum value, and then becomes larger gradually, as the parameter pincreases, as shown in FIG. 3. The position of this minimum value (p=p₁)is the ending position of the reflector.

In this manner, for detecting the existence positions of the reflectors14 a and 14 b, the reflector existence-region detection unit 19 changesthe AICp parameter p for the reflected light data in the object range asshown in FIG. 2 and detects the point for the best fitting of thereflected light data model M to be a boundary point between the regionwith the reflector pattern and the region without the reflector pattern,as shown in FIG. 3. Accordingly, the positions of the reflectors 14 aand 14 b are detected as the starting points and the ending points,respectively, and thereby it is possible to detect the reflectorpositions accurately.

Next, a calculation method of the twist amount of the rotating body 13in the twist amount calculation unit 21 will be described. The reflectedlight data at the reflector position specified by the reflector positionspecification unit 20 shows a reflection pattern where a strongintensity and a weak intensity are repeated periodically for eachrotation of the rotating body 13 as shown in FIG. 4. The upper part ofFIG. 4 shows the reflected light data A of the reflector 14 a, one ofthe pair of reflectors 14 a and 14 b, and the lower part thereof showsthe reflected light data B of the other reflector 14 b. The delay time tof the reflection pattern in the reflected light data B against thereflection pattern in the reflected light data A shows that the twistamount is generated in the rotating body 13.

The twist amount calculation unit 21 first obtains the rotation periodof the rotating body 13 from a correlation function of the reflectedlight data A. Now, a function F(t) is extracted from the reflected lightdata A, and then the correlation function f(t) of the reflected lightdata A is expressed by Formula (6). C is a shift time of a detectedsignal, t is the delay time, and d is a reflection pattern width of thereflected light data A.

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 6} \right\rbrack & \; \\{{\Phi\;{i(\tau)}} = {\left( {{1/2}\delta} \right){\sum\limits_{t = {C - \delta}}^{t = {C + \delta}}{{F\left( {t + \tau} \right)}{F(t)}}}}} & (6)\end{matrix}$

The delay time, which maximizes this correlation function f(t), isobtained. This calculation corresponds to an operation for checkingoverlap between the first detection signal (reflection pattern) and thenext detection signal (reflection pattern) by delaying the firstdetection signal temporally in the reflected light data A, and, when thedelay time t becomes close to the rotation period, the first detectionsignal becomes to coincide with the next detection signal and the valueof the correlation function f(t) becomes large. The delay time t at thispoint becomes the rotation period. This rotation period can be obtainedfrom the reflected light data B as well as the reflected light data A.

Meanwhile, the twist amount of the rotating body 13 is obtained from acorrelation function fi(t) between the reflected light data A and thereflected light data B. Now, a function G1(t) is extracted from theoutput signal of the reflected light data A and a function G2(t) isextracted from the output signal of the second detection signal, andthen the correlation function fi(t) is expressed by Formula (7). Ci is ashift time of the detection signal of the reflected light data A, t is adelay time between the reflected light data A and the reflected lightdata B, and di is a reflection pattern width of the reflected light dataA.

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 7} \right\rbrack & \; \\{{\Phi\;{i(\tau)}} = {\left( {{1/2}\delta} \right){\sum\limits_{t = {{C\; i} - {\delta\; i}}}^{t = {{C\; i} + {\delta\; i}}}{{G_{1}(t)}{G_{2}\left( {t + \tau} \right)}}}}} & (7)\end{matrix}$

The delay time, which maximizes this correlation function fi(t), isobtained. This calculation corresponds to an operation for checkingoverlap between the detection signal (reflection pattern) of thereflected light data A and the detection signal (reflection pattern) ofthe reflected light data B by delaying the detection signal of thereflected light data A. The delay time t maximizing the correlationfunction fi(t) corresponds to the twist amount of a drive axis in therotating body 13.

Next, a calculation method for the torque of the rotating body 13 in thetorque calculation unit 22 will be described. The torque calculationunit 22 calculates the torque Ft of the rotating body 13 from the twistamount (delay time) obtained by the twist calculation unit 21. Thetorque Ft of the rotating body 13 is obtained by Formula (6). K is atorsion spring constant of the drive axis in the rotating body 13, x isa distance between the reflector 14 a and the reflector 14 b, and T is arotation period of the rotating body 13.[Formula 8]Ft=2pKx·t/T  (8)

FIG. 5 is a flowchart of the torque measurement method measuring thetorque using the torque measurement device according to the firstembodiment of the present invention. First, the reflected light data ofthe laser light irradiating the surface of the rotating body 13 isinput, and the reflected light data is stored for a predetermined numberof rotations of the rotating body 13 (S1). Then, the existence regionsare detected for the pair of reflectors 14 a and 14 b, which areprovided on the surface of the rotating body 13 and has the spacing inthe axial direction, from the reflected light data of the rotating body13 (S2), and the twist amount of the rotating body 13 is calculated fromthe reflector positions specified by the existence regions of the pairof reflectors 14 a and 14 b (S3). Then the torque is calculated from thecalculated twist amount of the rotating body (S4).

According to the first embodiment, the existence regions of thereflectors 14 a and 14 b are detected and the reflector positions arespecified by the starting positions and the ending positions of thereflectors, and thereby the accuracy of the reflector position isimproved. Further, the twist amount of the rotating body 13 iscalculated from the reflector positions and then the torque of therotating body 13 is calculated, and thereby the accuracy of the torqueis improved. Moreover, these processing can be carried out in real time,and thereby the calculated torque of the rotating body can be used forreal-time monitoring control.

Second Embodiment

FIG. 6 is a block configuration diagram of a torque measurement deviceaccording to a second embodiment of the present invention. This secondembodiment provides an approximate reflector-position detection unit 24added to the first embodiment shown in FIG. 1 for detecting approximatepositions of the pair of reflectors 14 a and 14 b using the reflectedlight data of the rotating body 13 stored in the input data storagesection 18, and the reflector existence-region detection unit 19specifies the reflector positions by detecting the existence regions ofthe pair of reflectors 14 a and 14 b from the reflected light data inthe neighborhoods of the approximate positions of the pair of reflectors14 a and 14 b, which are detected by the approximate reflector-positiondetection unit 24. The same element as that in FIG. 1 is denoted by thesame symbol and repeated explanation will be omitted.

The approximate reflector-position detection unit 24 inputs thereflected light data of the rotating body 13, which is stored in theinput data storage section 18, and detects the approximate reflectorpositions of the pair of reflectors 14 a and 14 b from the reflectedlight data of the rotating body 13. The approximate reflector-positiondetection unit 24 carries out an arithmetic method of detecting theapproximate reflector positions as follows. First, the whole measuredwaveform in the reflected light data of the rotating body 13 is dividedinto small ranges having a range width D as shown in FIG. 7. Then, anaverage value H_(k) of an amplitude value x_(k) in the measured waveformis calculated for each of the ranges as shown in Formula (9). Thedivided range width D (D=2m) is determined to have approximately thesame size as a single piece size of the reflectors 14, for example.

$\begin{matrix}\left\lbrack {{Formula}\mspace{14mu} 9} \right\rbrack & \; \\{H_{k} = {\frac{1}{2m}{\sum\limits_{j = {- m}}^{j = m}x_{k + j}}}} & (9)\end{matrix}$

The reflected light data in the region of the reflector 14 a or 14 bshows a larger amplitude value than amplitude values of the peripheralregions thereof, and shows the larger range average value than theaverage values of the peripheral ranges. Accordingly, a local maximumposition of the range average value H_(k) in the small range is obtainedsequentially, and the local maximum position of the range average valueH_(k), which is larger than a predetermined value, is determined to bethe approximated reflector position. For example, in FIG. 7, since therange average values H₁₃ and H₃₀ are larger than the range averagevalues of the peripheral ranges and also larger than the predeterminedvalue, the local maximum positions of the range average values H₁₃ andH₃₀ are determined to be the approximate reflector positions. For thelocal maximum position of the range average value Hk, as shown in FIG.8, the range is divided further into a plurality of smaller ranges and aposition P_(k), which provides a local maximum of the smaller rangeaverage value, is determined to be the approximate position of thereflectors 14 a or 14 b.

The reflector existence-region detection unit 19 inputs the reflectedlight data in the neighborhood of the approximate positions of the pairof reflectors 14 a and 14 b, which are detected by the approximatereflector-position detection unit 24, from the input data storagesection 18, and detects and specifies the existence regions of the pairof reflectors 14 a and 14 b in real time from the reflected light datain the neighborhoods of the approximate positions of the pair ofreflectors 14 a and 14 b, using the arithmetic method described in thefirst embodiment.

The reflector positions of the pair of reflectors 14 a and 14 bspecified by the reflector existence-region detection unit 19 are inputinto the twist amount calculation unit 20, and the twist amount of therotating body 13 is calculated in real time. The twist amount of therotating body calculated by the twist amount calculation unit 20 isinput into the torque calculation unit 21 and the torque of the rotatingbody 13 is calculated in real time. The torque of the rotating body 13calculated by the torque calculation unit 21 is provided with the outputprocessing by the output processing unit 22 and output to outside fromthe signal processing device 16.

FIG. 9 is a flowchart showing the torque measurement method measuringthe torque using the torque measurement device according to the secondembodiment of the present invention. First, the reflected light data ofthe laser light irradiating the surface of the rotating body 13 isinput, and the reflected light data is stored for a predetermined numberof rotations of the rotating body 13 (S1). Then, the approximatepositions are detected for the pair of reflectors 14 a and 14 b, whichare provided on the surface of the rotating body 13 and has the spacingin the axial direction, from the reflected light data of the rotatingbody 13 (S2), and the existence regions of the pair of reflectors 14 aand 14 b are detected from the reflected light data in the neighborhoodsof the approximate reflector positions (S3), and then the twist amountof the rotating body 13 is calculated from the reflector positionsspecified by the existence regions of the pair of reflectors 14 a and 14b (S4). Finally, the torque is calculated from the calculated twistamount of the rotating body (S5).

According to the second embodiment, the reflector position specificationunit 20 carries out the detection processing for the existence regionsof the reflectors 14 a and 14 b only from the reflected light data inthe neighborhoods of the approximate positions of the reflectors 14 aand 14 b, and thereby does not need to carry out the detectionprocessing for the existence regions of the reflectors 14 a and 14 bfrom the whole reflected light data as in the first embodiment.Therefore, the second embodiment has an advantage of further reducingthe detection processing of the reflector positions in addition to theadvantage of the first embodiment.

Here, the method described in each of the foregoing embodiments can beapplied to each device as a computer-executable program stored in astorage medium, or can be applied to each device as acomputer-executable program transmitted via a communication medium.

The storage media for the present invention include such as a magneticdisk, a flexible disk, an optical disk (CD-ROM, CD-R, DVD, etc.) amagneto-optical disk (MO and the like), a semiconductor memory, etc.,and storage format thereof may be any type as far as the storage mediumis a program-storable and computer-readable storage medium. Further, thestorage media here are not limited to the media independent from acomputer and include a storage medium storing or temporarily storing aprogram which is transmitted and downloaded via a LAN or the Internet.

1. A torque measurement device provided with: a laser light outputdevice outputting laser light; a light transmitting/receiving deviceirradiating a surface of a rotating body with the laser light from thelaser light output device and also receiving reflected light thereof; apair of reflectors which is provided on the surface of the rotatingbody, having a spacing in an axial direction thereof and reflects theirradiating laser light from the light transmitting/receiving device ina predetermined reflection pattern; and a signal processing deviceobtaining a torque of the rotating body from the reflected lightreceived by the light transmitting/receiving device, the signalprocessing device, comprising: an input data storage section storingreflected light data of the laser light irradiating the surface of therotating body, the reflected light data being input according torotation of the rotating body; a reflector existence-region detectionunit detecting existence regions of the pair of reflectors bydetermining a point which minimizes AIC (Akaike's information criterion)of a model for the reflected light data of the rotating body, thereflected light data being stored in the input data storage section; atwist amount calculation unit calculating a twist amount of the rotatingbody from reflector positions which are specified by the existenceregions of the pair of reflectors, the existence regions being detectedby the reflector existence-region detection unit; and a torquecalculation unit calculating a torque from the twist amount of therotating body, the twist amount being calculated by the twist amountcalculation unit.
 2. A torque measurement device provided with: a laserlight output device outputting laser light; a lighttransmitting/receiving device irradiating a surface of a rotating bodywith the laser light from the laser light output device and alsoreceiving reflected light thereof; a pair of reflectors which isprovided on the surface of the rotating body, having a spacing in anaxial direction thereof and reflects the irradiating laser light fromthe light transmitting/receiving device in a predetermined reflectionpattern; and a signal processing device obtaining a torque of therotating body from the reflected light received by the lighttransmitting/receiving device, the signal processing device, comprising:an input data storage section storing reflected light data of the laserlight irradiating the surface of the rotating body, the reflected lightdata being input according to rotation of the rotating body; anapproximate reflector-position detection unit detecting approximatepositions of the pair of reflectors from the reflected light data of therotating body, the reflected light data being stored in the input datastorage section; a reflector existence-region detection unit detectingexistence regions of the pair of reflectors by determining a point whichminimizes AIC (Akaike's information criterion) of a model for the pairof reflected light data in neighborhoods of the approximate reflectorpositions which are detected by the approximate reflector-positiondetection unit; a twist amount calculation unit calculating a twistamount of the rotating body from reflector positions which are specifiedby the existence regions of the pair of reflectors, the existenceregions being detected by the reflector existence-region detection unit;and a torque calculation unit calculating a torque from the twist amountof the rotating body, the twist amount being calculated by the twistamount calculation unit.
 3. A non-transitory computer readable mediumcontaining computer instructions stored therein for causing a computerprocessor to perform the method steps of: inputting and storingreflected light data obtained by reflection of reflection patterns in apair of reflectors which is provided on a surface of a rotating body andhas a spacing in an axial direction thereof; detecting existence regionsof the pair of reflectors by determining a point which minimizes AIC(Akaike's information criterion) of a model for the reflected light dataof the rotating body; calculating a twist amount of the rotating bodyfrom reflector positions specified by the detected existence regions ofthe pair of reflectors; and calculating a torque from the calculatedtwist amount of the rotating body.
 4. A non-transitory computer readablemedium containing computer instructions stored therein for causing acomputer processor to perform the method steps of: inputting and storingreflected light data obtained by reflection of reflection patterns in apair of reflectors which is provided on a surface of a rotating body andhas a spacing in an axial direction thereof; detecting approximatepositions of the pair of reflectors from the reflected light data of therotating body; detecting existence regions of the pair of reflectors bydetermining a point which minimizes AIC (Akaike's information criterion)of a model for the reflected light data in neighborhoods of the detectedapproximate positions of the pair of reflectors; calculating a twistamount of the rotating body from reflector positions specified by thedetected existence regions of the pair of reflectors; and calculating atorque from the calculated twist amount of the rotating body.